Ophthalmic tests to determine the range and sensitivity of a subject's visual field are commonly performed (Anderson 1987, Johnson, 1983a). Many diseases of the eye, e.g., glaucoma and optic neuropathies, affect field of vision, and often these diseases are evidenced at an early stage, when treatment may be most effective, by reduction in visual field sensitivity. Additionally, the type and extent of many eye diseases, and the location of the disease along the visual pathway (i.e. the eye, the optic nerve, or the visual centers of the brain) can often be determined by visual field examination.
Presently there are a number of commercially-available visual field analyzers. The most widely used is the Humphrey Field Analyzer (Allergan Humphrey, Inc.). This device is a projection-type analyzer which performs static and suprathreshold static testing of the central and peripheral visual field (Lewis). Non-projection visual field analyzers are also used, although these analyzers have more limited capabilities than projection analyzers. Both type of analyzers are relatively expensive and non-portable.
In addition, the above analyzers require near-sighted or far-sighted users to wear corrective lenses, since a sharp focus is necessary for accurate testing. Also, during the examination, the user's head must be placed on a chin rest for an extended examination periods, e.g., up to a half-hour. This requirement may hinder testing due to artifacts introduced by the motion of the user to relieve discomfort.